Hypersomnia sleep apnea syndrome (HSA), the cessation of breathing for periods in excess of 10 seconds during a one hour sleep period, is a potentially life-threatening disorder, the incidence of which is estimated at over 2.5 million persons in the U.S. Two major types of sleep apnea have been described: (1) obstructive (upper airway), and (2) central. The obstructive type is characterized by a continuation of the respiratory effort during the apneic period, while the central is marked by loss of respiratory effort. A mixed type begins as central but continues as obstructive.
Obstructive sleep apnea is more common in men, 82-95% of cases, and is most often first identified in mid-life with the development of loud snoring and daytime somnolence. It is frequently accompanied by obesity, hypertension, cardiac irregularity and hemodynamic abnormalities. While not all persons who snore have sleep apnea, essentially all people affected with sleep apnea snore. See generally, Weitzman E. D., et al., Quantitative Analysis of Sleep and Sleep Apnea Before and After Tracheostromy in Patients with the Hypersomnia--Sleep Apnea Syndrome, Sleep Vol. 3, No. 314, pp 407-423 (1980).
In severe cases, the apnea incidences (apneic events) may be over 90/hour (see Cartwright et al., at p. 706, below). More moderate cases place those interruptions on the order of 3-50/hour. The cessation of breathing can last for periods of 45 seconds or more, and the patient is frequently aroused, gasping for breath. Death can occur through respiratory coma and/or associated heart problems.
In cases of obesity hypoventilation syndrome, loss of weight has resulted in reduction of snoring and/or apneic episodes. See Harman, E. M. et al., The Effect of Weight Loss on Sleep-Disordered Breathing and Oxygen Desaturation in Morbidly Obese Men, Chest Vol. 82, No. 3, pp 291-294 (Sept. 1982).
When obstructive sleep apnea is of serious proportions, surgery, specifically tracheostomy, may be the treatment of choice. However, patients often reject this choice as permanent tracheoctomy results in physical disability and psychological problems. See generally, Conway, W. A. et al., Adverse Effects of Tracheostomy for Sleep Apnea, JAMA Vol. 246, No. 4, pp 347-350 (July 24/31, 1981).
Another surgical approach is to reduce/remove deformities, or enlarge the airway. This approach includes uvulopalatopharygoplasty (UPPP), which is a removal of a portion of the soft palate to prevent closure of the airway in the pharynx region. See generally, Fujita, S., et al., Surgical Correction of Anatomic Abnormalities in Obstructive Sleep Apnea Syndrome: uvulopalatopharygoplasty, Otolaryngol Head Neck Surg., Vol. 89, pp 923-934 (Nov/Dec 1981).
A non-surgical approach involves applying positive airway pressure by use of low pressure mask. Continuous positive airway pressure (CPAP) provides a pneumatic splint for the nasopharyngeal airway. A variation is EPAP, expiratory positive airway pressure by a similar apparatus. See generally, Sullivan, C. E. et al., Reversal of Obstructive Sleep Apnea by Continuous Positive Airway Pressure Applied Through the Nares, The Lancet, Apr. 18, 1981, pp 862-865, and Mahadevia, A. K. et al., Effects of Expiratory Positive Airway Pressure on Sleep-Induced Respiratory Abnormalities in Patients with Hypersomnia-Sleep Apnea Syndrome, Am Rev Respir Dis 1983, Vol 128, pp 708-711.
Another non-surgical approach to reducing sleep apnea or stopping snoring has been the use of various types of oral cavity appliances. Several oral cavity appliances are the subject of U.S. patents. Strickland U.S. Pat. No. 3,434,470 is directed to a snore inhibiting device comprising a maxillary plate to decrease the air flow in the U-shaped spaced defined by the upper teeth. It has a resilient channel (U-shaped in cross section) which releasably grips the upper teeth, and a pair of overlapping moveable plate sections bridging the space between the left and right side teeth so that one size fits all. This device, in closing the oral cavity airway, functions the opposite of the instant invention. Further, it does not reposition the mandible.
Tepper U.S. Pat. No. 3,277,892 is directed to an apparatus for correcting protruding tongue problems which lead to malocclusion, speech defects (lisping) and incorrect swallowing. It is not directed to snore or apnea reduction. It employs a full palate retainer of the Hawley type and means for imparting an electrical shock when the tip of the patient's tongue is thrust forward to within 2 mm of the lingual surface of the upper incisors. Gibbons U.S. Pat. No. 2,844,142 is directed to a tongue retainer device which prevents an unconscious or semi-conscious person from swallowing the tongue blocking the trachea, or may be used during dental operations. The device comprises a pair of concentric rings, the inner suspended from the outer by a flexible strand. The large loop is placed over the jaw and the tongue is inserted in the smaller inner loop. The device does not reposition the mandible. Interestingly, Gibbons comments that horses have difficulty breathing when they run as the excitement and exertion causes swelling of the tongue, which results in the tongue falling backwardly into the throat. The device is said to improve breathing capacity of horses.
Ronn U.S. Pat. No. 1,401,646 is directed to a saliva ejector comprising a pair of bent perforated tubes which straddle the teeth. It is unrelated to snore reduction. Williams U.S. Pat. No. 1,498,219 is directed to a mouth prop for holding the mouth open and supporting cotton rolls during filling the teeth. It comprises a metal frame with a top plate spanning the palatal arch which is connected at the sides by a U-shaped upright frame. The bottom of the U-frame is connected to a loop that straddles the mandibular dentition. It is silent on how far open the jaw is forced, and does not appear to provide for anterior repositioning. It is silent on use as a snore-reducing device.
In a letter to The New England Journal of Medicine, entitled "Treatment of Obstructive Sleep Apnea with a Nocturnal Airway--Patency Appliance," Vol. 313, No. 6, Aug. 8, 1985, pp 386-387, Soll, B. A. and George, P. T. describe their work of modifying an "activator", a variant of the orthodontic appliance developed in 1902 by Pierre Robin for treatment of severe obstructive sleep apnea. They reference the Robin device to Salzmen, J. A., Practice of Orthodontics, Philadelphia J. B. Lippincott, 1966, but do not describe further its structure or function.
The Soll-George device can be described as an acrylic plastic retainer-like appliance which is placed between the teeth. I is molded so that all of the teeth fit into individual indentations. That is, the device apparently extends from the incisors in the front all the way around to the molars in the rear, both upper and lowers. Four clasps and a double maxillary arch wire serve to retain the device in position. While the NEJM text is silent, it appears from the photograph that the appliance substantially blocks the opening between the teeth with the exception of some small holes. The oral cavity air passage is substantially closed in an apparent attempt to insure that breathing occurs through the nasal passage rather than the mouth. The jaw is positioned somewhat opened with the lower jaw protruding forward. The amount of opening, as measured from the symphysis, is 9 millimeters inferior and 6 millimeters anteriorly, as compared to the normal closed position. Only one case was reported, with the apnea index (the number of apnea episodes per hour) dropping from 79 to 5.3.
Still another device is the TRD, an acronym for Tongue Retaining Device, described by Cartwright, R. D. et al. in The Effect of a Non-Surgical Treatment for Obstructive Sleep Apnea, JAMA Vol. 248, No. 6, pp 705-709, Aug. 13, 1982. This device is a soft copolymer plastic spacer, similar to a boxer or football player's mouthpiece, which holds the jaw in an open position. Its critical feature is use of a "lingual compartment", which is a large bubble protruding forwardly between the teeth, which receives the tongue. Apparently the tongue is retained in the bubble by negative pressure caused by surface tension. This device is worn at night and is reported to cut the apneic index in half, from about 36 to 18 episodes/hour. The TRD causes the patient's mouth to be open with the tongue sticking out. The bubble serves to retain the tongue in the extended position by negative pressure. There is no patency to the oral airway, i.e., the patient cannot breath through the mouth, the TRD completely closing the mouth opening thus forcing breathing through the nasal passages.
The "Bionator" is an appliance for quite a different purpose. This device is an appliance or retainer which causes the mouth to be open for the purpose of permitting the head of the condyle process to grow. In cases of juvenile jaw deformity or immaturity, the neck portion of the condyle at the distal end of the mandible is underdeveloped. With the lower jaw slightly opened, the growth of the mandibular process is stimulated through the application of tension. This juvenile bone corrective device is to be worn as much as possible, both day and night.
One of the disadvantages of the above-described types of appliances is that they can be quite uncomfortable. Muscle strain and the unnatural position causes pain and/or discomfort in the joint and tongue. The design of the Soll/George and TRD appliances does not permit unstrictured open mouth breathing. In addition, devices such as the TRD and CPAP/EPAP masks are cosmetically and psychologically disagreeable, and not condusive to shared sleeping arrangements.
Since the AMA estimates there are some 30 million Americans who snore and 2.5 million who have sleep apnea syndrome, there is still a great need for a simple device which reduces snoring and related apneic episodes, yet is comfortable to wear on a long-term basis, is cosmetically and psychologically acceptable, and provides for relatively full patency of the mouth airway (through the mouth breathing). This invention is directed toward solving those problems.